Natural enemies play a crucial role in the biological control of widespread weeds, offering an environmentally sustainable alternative to chemical herbicides. When prioritising weeds for biological control, several critical criteria must be considered to ensure effective and sustainable management which are captured in a new resource guide to help Pacific battlers in their fight against invasive species. 

The "Invasive Species Battler" series, which consists of a number of valuable resources produced in association with various technical partners, aims to share knowledge about common invasive species issues in the Pacific by providing information and case studies to help government agencies improve invasive species management. 

The Pacific region boasts incredible biodiversity, hosting numerous species found nowhere else on the planet. Currently, 2,189 single-country endemic species are documented. Sadly, 5.8% of these unique species are already extinct or survive only in captivity.

An alarming 45% of Pacific species face extinction risk, with the region experiencing some of the world's highest extinction rates. Invasive species pose the greatest threat to single-country endemic species in the Pacific. These invaders also significantly impact economies, trade, sustainable development, health, ecosystem services, and the resilience of ecosystems to natural disasters.

Pacific islanders, known for their self-reliance, depend heavily on their environment for sustenance. However, they also face common challenges with invasive species. Sharing regional experiences and lessons learned benefits families economically, culturally, and in daily life.

The Secretariat of the Pacific Regional Environment Programme (SPREP) Invasive Species team offers technical, institutional, and financial support to regional invasive species initiatives, working alongside other regional bodies. 

These key initiatives include coordination of projects and interventions by the Pacific Regional Invasive Species Management Support Service (PRISMSS), Pacific Invasive Learning Network (PILN), which connects invasive species practitioners across Pacific countries and territories and the Pacific Invasives Partnership (PIP), a regional coordinating body for agencies working on invasive species in multiple Pacific countries

The newest Battler Series guide focuses on understanding the negative impacts of weeds in Pacific island contexts and supports the prioritisation of established, widespread weeds for management, as part of a collection of Battler guides on managing weeds in the Pacific region. 

“It is important to determine which weeds cause the most harm and are most likely to be successfully controlled using natural enemies, and the cost and effort required for a biological control programme. With so many weeds needing to be managed, this approach helps to work out where best to start and focus available resources,” said Dr. Lynley Hayes, the PRISMSS Technical Lead for the Natural Enemies – Natural Solutions (NENS) programme.

The guide draws from training conducted by PRISMSS NENS Technical Lead Manaaki Whenua – Landcare Research (MWLR), New Zealand. It helps national managers assess the viability of using natural enemies, prioritize target species, and understand how climate change may affect weed populations and biocontrol effectiveness.

The PRISMSS NENS programme aims to reduce the impact of widespread invasive plants. It introduces safe natural enemies from the plants' native range to decrease their vigour.
“Using natural enemies to manage widespread weeds is a fantastic option for Pacific countries and the region. It provides a solution which overcomes several obstacles that we commonly face when managing weeds, such as a shortage of human resources for ongoing management and accessing difficult or inaccessible terrain,” said Mr David Moverley, SPREP Invasive Species Adviser. 

“The option to spread natural enemies across the Pacific, following rigorous testing of national non-target species, allows for economies of scale and offers regional solutions to national problems.” 

This technique has been used safely and successfully worldwide, including the Pacific islands, to manage weeds for more than 100 years. Safety measures include assessments of the natural enemies, testing whether they will use or interfere with other species native to the potential site of introduction or beneficial introduced species. 68 natural enemies have been released against 27 weed species in 18 countries and territories in the Pacific.
 
To effectively prioritize weed species for biological control measures using natural enemies, it is essential to quantify both their ecological disruption and economic impact accurately. By integrating data on biodiversity loss and financial costs incurred by different weed species, policymakers can make informed decisions about resource allocation towards sustainable management practices aimed at mitigating these pervasive threats.

PRISMSS will continue to work through the NENS programme to provide resources and technical assistance to Pacific island countries in the battle against invasive species. Information on invasive species management in the Pacific can be found on the SPREP Battler Resource Base (https://brb.sprep.org) and by request directly to PRISMSS.

For more information please contact:
Ms Lynley Hayes, Manaaki Whenua - Landcare Research - [email protected] or
Mr Nitish Narayan, Communications & Liaison Officer, PRISMSS, SPREP – [email protected] 

Pacific Regional Invasive Species Management Support Service (PRISMSS)

PRISMSS is a coordinating mechanism designed to facilitate the scaling up of operational management of invasive species in the Pacific.  PRISMSS brings together experts to provide support within the Pacific region with a focus on protection of indigenous biodiversity and ecosystem function.  As a service provider, PRISMSS provides a comprehensive suite of support services in a cohesive, effective, efficient, and accessible manner to Pacific Island countries and territories. 

This battler was completed under the Managing Invasive Species for Climate Change Adaptation in the Pacific (MISCCAP) project, funded to the Secretariat of the Pacific Regional Environment Programme (SPREP) from New Zealand MFAT. The MISCCAP project is a PRISMSS – NZ collaboration project developed to assist in establishing PRISMSS systems and infrastructure, upscaling on-the-ground support, and strengthening and mainstreaming invasive species management across the Pacific.

The GEF 6 Regional Invasives Project (RIP) is funded by the Global Environment Facility, implemented by the United Nations Environment Programme, and executed by the Secretariat of the Pacific Regional Environment Programme. The Project works primarily in the Marshall Islands, Niue, Tonga, and Tuvalu and has a regional component. Implementation of the GEF 6 RIP is supported by PRISMSS.

The PRISMSS Natural Enemies – Natural Solutions (NENS) programme aims to lower the impact of widespread invasive plants by reducing their vigour by introducing safe natural enemies from the area where they, and their host plant, originate. There are many opportunities for spreading existing agents available in the Pacific to new countries, introducing agents available outside the Pacific, and developing new options for the Pacific. https://www.sprep.org/prismss/natural-enemies-natural-solutions   

The NENS programme has created a web resource to help inform decisions about activities and biocontrol for Pacific weeds: NENS Option, https://nensoption.com 

Learn more about PRISMSS